* [B.A.T.M.A.N.] [PATCH maint] batman-adv: wait for rtnl in batadv_store_mesh_iface instead of failing if it is taken
@ 2013-05-28 15:32 Matthias Schiffer
2013-05-28 15:42 ` Simon Wunderlich
0 siblings, 1 reply; 3+ messages in thread
From: Matthias Schiffer @ 2013-05-28 15:32 UTC (permalink / raw)
To: b.a.t.m.a.n
The rtnl_lock in batadv_store_mesh_iface has been converted to a rtnl_trylock
some time ago to avoid a possible deadlock between rtnl and s_active on removal
of the sysfs nodes.
The behaviour introduced by that was quite confusing as it could lead to the
sysfs store to fail, making batman-adv setup scripts unreliable. As recently the
sysfs removal was postponed to a worker not running with the rtnl taken, the
deadlock can't occur any more and it is safe to change the trylock back to a
lock to make the sysfs store reliable again.
Signed-off-by: Matthias Schiffer <mschiffer@universe-factory.net>
---
sysfs.c | 5 +----
1 file changed, 1 insertion(+), 4 deletions(-)
diff --git a/sysfs.c b/sysfs.c
index 15a22ef..929e304 100644
--- a/sysfs.c
+++ b/sysfs.c
@@ -582,10 +582,7 @@ static ssize_t batadv_store_mesh_iface(struct kobject *kobj,
(strncmp(hard_iface->soft_iface->name, buff, IFNAMSIZ) == 0))
goto out;
- if (!rtnl_trylock()) {
- ret = -ERESTARTSYS;
- goto out;
- }
+ rtnl_lock();
if (status_tmp == BATADV_IF_NOT_IN_USE) {
batadv_hardif_disable_interface(hard_iface,
--
1.8.3
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [B.A.T.M.A.N.] [PATCH maint] batman-adv: wait for rtnl in batadv_store_mesh_iface instead of failing if it is taken
2013-05-28 15:32 [B.A.T.M.A.N.] [PATCH maint] batman-adv: wait for rtnl in batadv_store_mesh_iface instead of failing if it is taken Matthias Schiffer
@ 2013-05-28 15:42 ` Simon Wunderlich
2013-06-04 9:14 ` Marek Lindner
0 siblings, 1 reply; 3+ messages in thread
From: Simon Wunderlich @ 2013-05-28 15:42 UTC (permalink / raw)
To: The list for a Better Approach To Mobile Ad-hoc Networking
[-- Attachment #1: Type: text/plain, Size: 1375 bytes --]
On Tue, May 28, 2013 at 05:32:32PM +0200, Matthias Schiffer wrote:
> The rtnl_lock in batadv_store_mesh_iface has been converted to a rtnl_trylock
> some time ago to avoid a possible deadlock between rtnl and s_active on removal
> of the sysfs nodes.
>
> The behaviour introduced by that was quite confusing as it could lead to the
> sysfs store to fail, making batman-adv setup scripts unreliable. As recently the
> sysfs removal was postponed to a worker not running with the rtnl taken, the
> deadlock can't occur any more and it is safe to change the trylock back to a
> lock to make the sysfs store reliable again.
>
> Signed-off-by: Matthias Schiffer <mschiffer@universe-factory.net>
Reviewed-by: Simon Wunderlich <siwu@hrz.tu-chemnitz.de>
Thanks for posting,
Simon
> ---
> sysfs.c | 5 +----
> 1 file changed, 1 insertion(+), 4 deletions(-)
>
> diff --git a/sysfs.c b/sysfs.c
> index 15a22ef..929e304 100644
> --- a/sysfs.c
> +++ b/sysfs.c
> @@ -582,10 +582,7 @@ static ssize_t batadv_store_mesh_iface(struct kobject *kobj,
> (strncmp(hard_iface->soft_iface->name, buff, IFNAMSIZ) == 0))
> goto out;
>
> - if (!rtnl_trylock()) {
> - ret = -ERESTARTSYS;
> - goto out;
> - }
> + rtnl_lock();
>
> if (status_tmp == BATADV_IF_NOT_IN_USE) {
> batadv_hardif_disable_interface(hard_iface,
> --
> 1.8.3
>
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^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [B.A.T.M.A.N.] [PATCH maint] batman-adv: wait for rtnl in batadv_store_mesh_iface instead of failing if it is taken
2013-05-28 15:42 ` Simon Wunderlich
@ 2013-06-04 9:14 ` Marek Lindner
0 siblings, 0 replies; 3+ messages in thread
From: Marek Lindner @ 2013-06-04 9:14 UTC (permalink / raw)
To: b.a.t.m.a.n
On Tuesday, May 28, 2013 23:42:48 Simon Wunderlich wrote:
> On Tue, May 28, 2013 at 05:32:32PM +0200, Matthias Schiffer wrote:
> > The rtnl_lock in batadv_store_mesh_iface has been converted to a
> > rtnl_trylock some time ago to avoid a possible deadlock between rtnl and
> > s_active on removal of the sysfs nodes.
> >
> > The behaviour introduced by that was quite confusing as it could lead to
> > the sysfs store to fail, making batman-adv setup scripts unreliable. As
> > recently the sysfs removal was postponed to a worker not running with
> > the rtnl taken, the deadlock can't occur any more and it is safe to
> > change the trylock back to a lock to make the sysfs store reliable
> > again.
> >
> > Signed-off-by: Matthias Schiffer <mschiffer@universe-factory.net>
>
> Reviewed-by: Simon Wunderlich <siwu@hrz.tu-chemnitz.de>
Applied in revision 96cd772.
Thanks,
Marek
^ permalink raw reply [flat|nested] 3+ messages in thread
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2013-05-28 15:32 [B.A.T.M.A.N.] [PATCH maint] batman-adv: wait for rtnl in batadv_store_mesh_iface instead of failing if it is taken Matthias Schiffer
2013-05-28 15:42 ` Simon Wunderlich
2013-06-04 9:14 ` Marek Lindner
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